The present invention pertains to a fluid transfer and monitoring method and device for delivering a predetermined amount of fluid. More particularly, the present invention pertains to a method and device for the direct measurement and control of the precise amount of fluid transferred.
Hospitals, pharmacies and laboratories are required to deliver a predetermined amount of fluid to be analyzed, to fill unit dosage syringes, medical containers or other receptacles with identical, repeatable quantities. It is important that a high degree of accuracy as well as cleanliness and sterility be maintained in these operations. Further, a high productivity rate is desirable along with the high standards of accuracy, cleanliness and sterility to efficiently use personnel, and minimize cost without sacrificing quality.
A known manual apparatus and process for transferring fluids utilizes a solution transfer system including a receiving container and a Y-transfer set. The Y-transfer set includes two separate tubes, each having an end attached to a common juncture by which solutions delivered through the tubes will pass through the juncture into the receiving container. The other end of one tube of the set is attached to one solution container and the other end of the other tube of the set is attached to another solution container. The desired volume of each solution being transferred to the receiving container is controlled by a clamp placed on each tube. The solutions may be allowed to flow into the receiving container by gravity flow. However, it has been found to be useful to transfer the solutions under the influence of a vacuum applied to the receiving container. When the receiving container is a flexible plastic container, the vacuum is created in a vacuum chamber into which the container is placed.
It has been known in the past that to ensure sterility during the transfer of solutions, the process should be performed under a laminar flow hood. Laminar flow hoods are used for reducing the risk of airborne contamination of such solutions. These units operate by taking room air and passing it through a pre-filter to remove gross contaminates, such as dust and lint. The air is then compressed and channeled through a bacterial retentive filter in the hood in a laminar flow fashion. The purified air flows out over the entire work surface of the hood in parallel lines at a uniform velocity. The bacterial retentive type of filter is designed to remove all bacteria from the air being filtered.
Transferring solutions under a laminar flow hood aids in preventing airborne contamination, but it is relatively cumbersome and expensive and would not be useful for eliminating any other source of contamination, such as contamination caused by handling. When using a hood the operator may inadvertently perform the work at the end or outside of the hood and not within the recommended space, at least six (6) inches within the hood, which insures the benefits of the air being purified. Time must be taken and care must be exercised to maintain a direct open path between the filter and the compounding area. Solution bottles and other nonsterile objects cannot be placed at the back of the hood work area next to the filter because these objects could contaminate everything downstream and disrupt the laminar flow pattern of the purified air. Also, in using a laminar flow hood, it is necessary routinely to clean the work surface of the hood before any compounding is performed.
Thus, the prior art manual or semi-manual apparatuses and processes discussed above are disadvantageous due to their inefficiency for filling large numbers of containers encompassing extensive number of hand operations which are labor intensive, time consuming and can be error prone.
Modern machines are capable of transferring fluids at high speeds with some degree of accuracy. However, the methods employed in these machines to monitor the delivery of a predetermined amount of fluid require actual measurement of the flow speed of the fluid. In measuring the flow speed of fluids, special purpose dedicated monitoring devices such as air detectors, ultrasonic transducers, doppler transmit/receive devices are employed. These devices only measure the fluid flow indirectly and therefore are vulnerable to inaccuracies as well as not providing reproducible results. This, of course, is a major drawback when it is required to deliver a repeatable, accurate predetermined amount of fluid quickly and efficiently.
Another known method of attaining accuracy in the transfer of a predetermined amount of fluid is by a volumetric chamber. This method requires a volume chamber which is costly to manufacture due to the requirement of precise tolerances to maintain an exact volume therein. The method is also slow and interrupts the laminar flow of the fluid to be transferred. Further, air in the volume chamber can effect the determination of the amount transferred.
The method and device of the present invention overcomes the above-discussed disadvantages. Further, the present invention provides for the actual monitoring of the fluid being transferred to achieve a quick, accurate, reproducible transfer of fluids. The present invention therefore provides for high productivity while maintaining high standards for accuracy and repeatability.
A process and apparatus that can utilize the hereindescribed invention is disclosed and claimed in co-pending U.S. application Ser. No. 391,759 filed concurrently herewith, in the names of Carl Miller and Lawrence R. Hogan for HIGH SPEED BULK COMPOUNDER which application is assigned to the assignee of the present invention and is incorporated herein by reference.
As disclosed therein, quick and accurate delivery of fluids is accomplished by sequentially controlled peristaltic pumps operatively connected between the solution containers and a receiving container. A controller receives data from an operator on the amount, by volume, of each solution to be compounded and its specific gravity. The comparison of this data to the weight sensed in a collection container permits the controller to sequentially operate the pumps. The controller is also able to monitor various process conditions. Failure to achieve these process conditions results in an automatic shutdown of the operation.